1. Field of the Invention
This invention relates to a self-aligning roller bearing with retainer which can be installed in all kinds of mechanical devices, for example, to support a rotating shaft inside a housing.
2. Description of the Prior Art
Conventionally, in order to freely rotatably support a shaft loaded inside a housing, a self-aligning roller bearing with retainer as shown in FIGS. 9 thru 11 was used. In FIG. 10 and 11, the rollers 3 are illustrated by phantom lines.
This kind of self-aligning roller bearing with retainer comprises an outer ring 1, an inner ring 2 arranged concentric with the outer ring 1, a plurality of rollers 3 with cylindrically spherical surface located between the outer ring 1 and the inner ring 2 and arranged so that they turn freely, and retainers 4 (press retainers) which are made by press-forming a metal plate and used for preventing the rollers 3 from becoming separated.
An outer race 5, having a spherical concave surface with a single center, is formed on the inner peripheral surface of the outer ring 1. Also, a pair of inner races 6 are formed on the outer peripheral surface of the inner ring 2 and juxtaposed in the width direction (left and right direction of FIG. 9) to face the outer race 5. The rollers 3 are formed generally symmetrically in the direction of roller axis with the section having the largest diameter located in the axial center of the roller length, and arranged in two rows between the outer race 5 and the pair of inner races 6 so that they turn freely.
The retainer 4 has a main part 7 having a frustum shape, an outward flange 8 extending outward in the radial direction from the peripheral edge of the larger diameter section of the main part 7, and an inward flange 9 extending inward in the radial direction from the peripheral edge of the smaller diameter section on the main part 7.
The main part 7 has a plurality of ribs 16 to connect the outward and inward flanges as shown in FIG. 13, such that there are a plurality of pockets 10 formed in the main part 7, wherein each of the pockets 10 supports one of the rollers 3 so that it turns freely. In FIG. 9, the edge of the pocket 10 of the main part 7 behind the right roller 3 is illustrated by dotted lines. In FIG. 10, the ribs 16 behind the outward flange 8 is also illustrated by dotted lines.
By locating this main part 7 on the radially inside of the pitch circle of the rollers 3 (the circle that connects the pair of center axes of the rollers 3), the pockets 10 prevent each of the rollers 3 from falling out in the radially inward direction of main part 7.
In addition, the roller bearing has a guide ring 11 which is freely rotatably located between the two rows of rollers 3.
The outward flanges 8 of the pair of retainers 4 are guided by the guide ring 11 with the outer peripheral edge of the outward flange 8 fitted into the inside peripheral surface of the guide ring 11. Also, the inward flanges 9 are guided by the inner ring 2 with the inner peripheral edge of the inward flanges 9 fitted onto the outer peripheral surface of an axial edge section of the inner ring 2.
There is an engagement relationship between the rollers 3 and the retainers 4 to prevent the rollers 3 from falling out of the pockets 10. For example, as disclosed in Japanese Patent First Publications No. (Showa) 62-141313 and No. (Heisei) 2-180314, a projection 12 is formed toward the rollers by inclining in an offset manner a portion of the outward flange 8 at the circumferentially middle portion of each of the pockets 10 near the outer perpheral edge of each of the outward flanges 8. Also, a concave section 13 is formed on the end face of the rollers 3 in the location which faces the projection 12. By bringing the tip of the projection 12 in engagement with the concave section 13, the rollers 3 held inside each of the pockets 10 are prevented from falling out in the radially outward direction. As a result, the rollers 3 are supported so that they rotate freely inside the pockets 10 and cannot fall out of the pockets 10 in either the inward or outward radial direction.
In the self-aligning roller bearing with retainer described above, when a rotating shaft is supported inside the housing, the outer ring 1 is inserted into and fixed to the the housing with the inner ring 2 fixed from outside to the rotating shaft. When the inner ring 2 rotates together with the rotating shaft, the rollers 3 turn allowing the rotating shaft to rotate. If the axis of the housing does not coincide with the axis of the rotating shaft, the inner ring 2 is aligned inside the outer ring 1 to compensate for the non-coincidence, and, because the outer race 5 is formed with a single spherical surface, rotation of the rollers 3 is smooth even after compensation of the non-coincidence.
However, the following problems must be solved for this prior art self-aligning roller bearing with retainer.
The rollers 3 held inside the pockets 10 are prevented from falling out in the radially outward direction because the concave section 13 on the end face of the rollers 3 comes into engagement with the projection 12 on the outer edge of the outward flange 8. However, in order to prevent the rollers 3 from falling out with assurance, it is necessary that the projection 12 and the concave section 13 securely come together. Consequently, the depth of the concave section 13 must be large for better engagement with the projection 12, or the stiffness of the outward flange 8 with the projections 12 formed in it must be increased (strengthened).
On the other hand, when the rollers 3 are installed inside the pockets 10, it is necessary to elastically deform the outward flange 8 with the projection 12 outward, so that the roller 3 are snapped into the pocket 10 as shown in FIG. 12. In order to perform this installation easily, it is necessary to make the concave section 13 shallow for easy engagement and disengagement between the projection 12 and the concave section 13 and to make stiffness of the outward flange 8 small (weak) for easy snapping.
Therefore, conventionally, the plate thickness of the metal plate used to make the retainer 4 was made thin so that the rollers 3 could be securely installed or snapped into the pockets 10, resulting in that the strength of the retainer 4 was lowered so long as the retainer 4 was made thin.